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New Device Prevents Awakening During Surgery

February 16, 1998

It's a cause of great anxiety for patients undergoing surgery. Recent, publicized reports of surgical patients who unexpectedly regain consciousness but are unable to communicate have anesthesiologists searching for ways to gauge doses of surgical anesthetics more accurately.

A new device, the Bispectral Index (BIS), is being introduced at Strong Memorial Hospital to help doctors calibrate drug doses to prevent patients from regaining " awareness" in the operating room. A flexible sensor which attaches to the patient's forehead records brain waves with a specialized EEG machine, giving anesthesiologists a direct measure of how deeply the patient is asleep. Studies have shown that monitoring patients with the BIS has led to improved patient outcomes, including better overall recovery, and more alert patients who are eligible for earlier discharge from the recovery room.

Traditionally, doctors relied on blood pressure and other vital signs to monitor sleep level. However, this method measures the effect of pain killers only -- not the full combination of pain killers, sedatives and paralytic drugs that produce anesthetized sleep. True sleep level can only be measured through brain waves.

" With this equipment, anesthesiologists can now give the precise amount of drug to ensure that the patient doesn't regain consciousness, but is not over-medicated," said Ronald S. Litman, D.O., director of Pediatric Anesthesiology at Strong Memorial Hospital and assistant professor of Anesthesiology and Pediatrics. To avoid the chance of patient awareness during surgery, anesthesiologists have traditionally tended to administer slightly more anesthetic than needed. " Essentially, this tool allows us to customize anesthesia to the particular patient, which could be especially useful in children's surgeries," Litman said.

Studies conducted at Emory University estimate that unexpected wake-ups occur in at least 40,000 of the nation's 20 million surgeries. In most cases, pain killers continue to work, but the patient becomes aware of his or her surroundings.